The invention relates to a process for discharging pneumatically conveyable loose material (also known as bulk material) from a conically downwardly tapering hopper (outlet) of an internal pressure-loadable silo into a pneumatic product conveyor line by means of compressed air which is blown through and loosens the material. Compressed air is admitted into the hopper via an air chute along the walls in the area of the hopper opening and via nozzles in the hopper walls above the air chute.
In a known process of this type, air is optionally blown into the silo either via the air chute or via the nozzles, or both via the air chute and via the nozzles, in order to loosen the product therein. The operating pressure in the silo uses as a result of admission of air, and the product is discharged into the product conveyor line.
There are a large number of loose materials, particularly those with organic constituents such as, for example, bacteriochemically prepared compost, which tend to clog the silo. Loose materials of this type form bridges extending from one wall to the other in the tapering hopper, as well as chimneys which extend through the entire loose material down into the hopper opening. Consequently, the conveyor air finds the path of least resistance and flows past the loose material into the product conveyor line without carrying with it any noteworthy quantities of loose material.
Attempts have been made to break up obstructions in pneumatic loose material conveyor systems by blowing in compressed air surges into the obstructed area. Air speeds close to the speed of sound have been used in this connection.